Combination lock



Aug. 25, 1959 H. c. MILLER 2,900,813

COMBINATION LOCK Filed July 5, 1957 5 Sheets-Sheet l INVENTOR flazZyMZ/er Aug. 25, 1959 c, MlLLER 2,900,813

COMBINATION LOCK Filed July 5. 1957 I v 3 Sheets-Sheet 2 ATTORNEYS Aug. 25, 1959 H. c. MILLER COMBINATION LOCK 5 Sheets-Sheet 3 Filed July 5. 1957 film QMZZZZ a We ATTORNEYS COINATEQN LOCK Harry C. Miller, Rochester, N.Y.

Application July 5, 1957, Serial No. 676,115

9 Claims. (Cl. 70-333) The present invention relates in general to combination locks and more particularly combination locks having means incorporated therein for resisting surreptitious entry techniques of manipulation thereof by unauthorized persons.

Conventional locks of the class known as combination locks usually comprise three tumbler wheels which are loosely journalled in coaxial longitudinally spaced relation for rotation Within a lock casing on a tubular arbor or tumbler post projecting inwardly of the casing from the front wall thereof. The lock dial, which usually has 100 peripheral calibration marks thereon, is affixed to a dial spindle which extends through the bore of the tumbler post and has keyed to the inner end thereof a disk-like drive cam which is likewise arranged coaxially with and spaced rearwardly from the tumbler Wheels. A drive pin projects forwardly from the drive cam and has a lost motion connection through a conventional fly with the rearmost tumbler wheel to drive the tumbler wheel in selected rotation to the drive cam. A similar lost motion connection is provided between each of the successive tumblers so that each of the tumblers may be driven upon selected rotation of the drive cam. Conventionally, the lost motion connection between the drive cam and the rearmost tumbler and between the other successive pairs of tumblers provides about 355 degrees of lost motion. Each of the tumbler wheels and the drive cam are provided with a peripheral notch or gating at a selected radial position on the cam or tumbler wheel.

A fence lever which is pivotally connected at one end to a reciprocative bolt slid'abl'y supported in the lock casing is provided with a depending nose at the opposite end which is designed to ride upon the drive cam peiiphery and has a bar or fence projecting laterally therefrom in overlying relation with the tumbler peripheries in axial alignment with the tumbler wheels. The position of the fence in relation to the length of the fence lever nose is usually such that the fence is spaced slightly from the tumbler peripheries when the fence lever nose is riding on the drive cam periphery.

In the normal operation of such combination locks, the dial is rotated four full revolutions in one direction until the dial marking representing a selected number is aligned with the fixed index marking, which disposes the gating of the forwardmost tumbler wheel in registry with the fence. Then the dial is rotated inan opposite direction for three revolutions to bring the dial marking representing the second number of the combination in alignment with the indeX mark and position the middle tumbler wheel gating in alignment with the fence. Then the dial is rotated in the first direction two full revolutions to position the dial marking representing the third number of the combination in alignment with the index mark to properly position the rearmost tumbler wheel gating. Then the dial is rotatedin the opposite direction to align the Zero dial mark with the index mark and position the drive cam gating in registry with the fence level' nose, whereupon" the fence lever nose drops into th'e' 'drivecam gating and the fence drops into the registered tumbler gatings. Further rotation of the dial in the same direction through approximately degrees effects withdrawal of the bolt.

It will be noted that when the tumbler wheel gatings are out of registry with the fence and the dial is turned to the proper position to dispose the drive cam gating below the fence lever nose, the fence lever nose will drop slightly into the drive cam gating until the fence bears upon the tumbler peripheries. The rotation of the dial through small arcs in opposite directions from this position will bring the opposite surfaces of the drive cam gating into contact with the fence lever nose. The points at which the fence lever nose contacts these opposite surfaces at the entrance to the drive cam gating are known as the left and right contact points of the fence lever and may be detected by coordination of the senses of touch and sight by the person manipulating the dial. A variation in the relation and feel of these contact points occurs when one of the tumbler gatings is positioned beneath the fence, which is distinguishable from the relation and feel of these contact points when all of the tumbler gatings are out of registry with the fence. Because of the fact that the drive cam can be rotated through a sufficient arc when the fence is in contact with the tumbler peripheries to reveal the contact points of the fence lever nose, the location of the three tumbler wheel gatings can be determined by unauthorized persons by following a now Well known lock manipulation procedure.

Various modifications in combination lock structure have heretofore been resorted to to defeat detection of the lock combination in this manner. Among these is the lock structure disclosed in my prior Patent No. 2,575,674

wherein a bridging slide is mounted on the rear face of the drive cam and has a curved end portion conforming to the curvature of the drive cam periphery which normally overlaps the drive cam gating and forms a smooth continuation of the drive cam periphery to support the fence lever'nose when the drive cam gating is in registry with the fence lever nose. An inner spindle extends through the dial spindleand is coupled at its inner end to the bridging slide and at its outer end to a knob which is in exposed condition, whereby upon rotation of the knob and inner spindle, the slide may be shifted radially of the drive cam to expose the drive cam gating for reception of the fence lever nose. When the bridging slide is in projected position exposing the drive cam gating to entry of the fence lever nose, stop members on the lock casing are disposed in the path of movement of a portion of the slide to limit rotation of the drive cam to an extent which will prevent detection of contact points for the fence lever nose.

It has been determined, however, that the security of this lock may be adversely affected in time if the portion of the bridging slide which is projected beyond the drive cam periphery becomes worn, as by abrasion against adjacent surfaces of the lock casing. It is possible that the projected end surface of the bridging slide may become worn to a depth equal to the'spacing of the fence from the tumbler Wheel peripheries when the fence lever n'ose engages the drive cam periphery. In such a case, the slide may be only partially projected from the position wherein it bridges the drive cam gating to lower the fence into contact with the tumbler peripheries and lower the fence lever nose into at least the entrance to the drive cam gating without projecting the slide suffic'iently to permit the stop members. to limit rotation of the 'drive cam. In this condition, the dial could be manipulated to permit sensing of the contact points and detectionof the combination of the lock.

Other modifications have involved the provision of shielding members which normally resiliently restrain the fence lever in an elevated position wherein both the fence and the fence lever nose are spaced from the tumbler peripheries and drive cam periphery, together with either an axially shiftable dial spindle and drive cam or axially shiftable means associated there'- with for disengaging the shielding means from the fence lever to permit the fence and fence lever nose to drop into engagement with their associated components. These variations employ forwardly projecting pins on the rear wall of the lock casing to be engaged in accommodating apertures or slots in the driving cam or associated axially shiftable means when the same are shifted rearwardly to a sufiicient degree to disengage the shielding means from the fence lever and thereby prevent rotation of the dial and drive cam when the fence lever is released and the tumbler gating are not all in registry with the fence. It is also possible to breach the security of these locks when the shielding means becomes sufficiently worn through use to release the fence lever and the drive cam before the associated axially shiftable means is interlocked with the pin on the rear wall of the lock casing. Such premature release of the fence lever will permit sensing of the contact points and detection of the combination in the manner described above.

It will be noted that a common feature of each of the above-described modifications for improving the security of combination locks is the provision of means which will maintain the fence lever nose out of operative contact with the drive cam gating and keep the fence spaced from the tumbler peripheries during rotation of the dial and drive cam to adjust the tumblers to the combination,

together with means which prevent rotation of the drive cam to a sufficient degree to sense the contact points thereof when the fence has been lowered into engagement with the tumbler peripheries. So long as the fence lever nose is not permitted to enter to any extent into the drive cam gating when the fence is in contact with the tumbler peripheries, it is not possible to detect the combination of the lock in the manner previously described.

An object of the present invention, therefore, is the provision of a novel combination lock which will effectively defeat surreptitious detection of the combination of the lock by unauthorized persons.

Another object of the present invention is the provision of a novel combination lock mechanism having means for selectively preventing and permitting opera-- tive coupling of the fence lever with the drive cam and means for restraining manipulation of the drive cam to the extent necessary for surreptitious detection of the combination when the fence lever is operatively coupled with the drive cam.

Another object of the present invention is the provision of novel combination lock construction having protective means which are normally conditioned to prevent coaction between the fence lever and drive cam in a manner which would enable detection of the combina tion of the lock and means for shifting the protective means to a disabled position permitting coupling of the drive cam and fence lever, wherein means are provided for insuring that the operation of the drive cam will be restrained in a manner preventing surreptitious detection of the combination when the fence lever is operatively coupled with the drive cam.

Another object of the present invention is the provision in a combination lock mechanism of the type having a shielding member normally positioned to prevent entry of the fence lever nose into the drive cam gating during adjustment of the drive cam and tumblers, means for shifting said shielding member between shielding and non-shielding positions in response to movement of an adjusting member, and means for imposing a selected restraint on rotation of the drive cam when the shielding member is shifted fully to non-shielding position, of

means associated with said adjusting member for storing up energy during a preselected initial adjustment thereof and for automatically releasing the shielding member to respond to the stored up energy and shift under the influence thereof between shielding and non-shielding positions when the adjusting member reaches a selected position.

Other objects, advantages and capabilities of the present invention will become apparent from the following detail description taken in conjunction with the accompanying drawing showing several preferred embodiments of the invention.

In the drawings:

Figure 1 is a vertical section view of a preferred embodiment of a combination lock made in accordance with the present invention, taken along the line 1-1 of Figure 2;

Figure 2 is a vertical section view taken on the line 22 of Figure 1;

Figure 3 is a partial vertical section view showing parts of the lock with the slide in bridging position;

Figure 4 is an exploded perspective view of the drive cam, the bridging slide, and the associated actuating mechanism;

Figure 5 is a horizontal section view of a modified form of combination lock embodying the present invention, taken along the line 55 of Figure 6;

Figure 6 is a rear elevational view of the lock of Figure 5 with the rear cover removed;

Figure 7 is a fragmentary exploded perspective view of the coupling mechanism between the sections of the inner spindle of the embodiment illustrated in Figure 5;

Figure 8 is a rear elevational view of a combination lock embodying another modified form of the present invention, with parts of the rear cover plate removed;

Figure 9 is a horizontal section view taken along the line 99 of Figure 8; and

Figure 10 is a vertical section view taken along the line 10-10 of Figure 8.

Referring to the drawings, wherein like reference characters designate corresponding parts throughout the several figures, and particularly to Figures l-4, inclusive, showing one preferred embodiment of the invention, there is illustrated a combination lock, generally indicated by the reference character 10, which corresponds substantially to the structure for the combination lock disclosed in my prior Patent No. 2,575,674. The lock comprises the lock casing 11 of rearwardly opening rectangular configuration mounted on a safe door or the like and closed by a rear cover plate 12. Within the lock casing are the usual tumbler wheels 13, 14 and 15 rotatably journalled in coaxial longitudinally spaced relation on the rearwardly projecting tubular tumbler post 16 and each having a peripheral gating or recess 17. A substantially cylindrical drive cam 18 is keyed to a tubular dial spindle 19 which projects through the tumbler post 16 and through the safe door and has the usual dial 20 fixed to the end thereof projecting forwardly of the safe door. The drive cam 18 has the usual drive pin 21 which projects from the forward face of the drive cam into a concentric groove in the rear face of the rearmost tumbler 13 to engage the projection of the usual fly associated with the rearmost tumbler and shift the same into engagement with a shoulder integral with the tumbler 13 and projecting into the recess. A similar lost motion driving connection is provided between the tumblers 13 and 14 and tumblers 14 and 15.

The fence lever 22 is pivotally mounted on the bolt 23 and is provided with a fence 24 which overlies the peripheries of the tumblers 13, 14 and 15 and a depending nose 25 which is adapted to be projected into the peripheral gating 26 of the drive cam 18. The length of the fence lever nose 25 in relation to the position of the fence 24 is such that the fence is spaced slightly from the tumbler peripheries when the nose 25 is riding or bridging position as illustrated in Figure 3.

gamers on the drive cam periphery. The rearwardly disposed portion of the drive cam 18 isprovided with a guideway having laterally spacedguitl'e surfaces positioned symmetrically with respect to a diametric axis of the drive cam between which a bridging slide 27 is supported. The upper and lower ends 28 and 29 are arcuately curved to conform to the curvature of the drive cam. periphery and positioned to form continuations thereof so that an uninterrupted cylindrical surface is presented to the fence lever nose 25 by the drive cam when'the slide is in closed The central portion of the slide is provided with an opening suchas that indicated at 30 having gear teeth 31 along one of the lateral bounding surfaces of the opening 30 adapted to mesh with a small pinion 32 mounted on an inner spindle 33 extending through a complementary bore in the tubular dial spindle 19 to aposition adjacent the forward edge of the knob 34 associated 'with the dial 20. A suitable slide control knob 35 is fixed to the forward end of the inner spindle 33 and exposed at the forward face of the dial knob 34 to be rotated through approximately 180 degrees when the dial is in a preselected position as will be hereinafter described to project the slide 27 to the position illustrated in Figure 2 wherein the drive cam gating 26 is exposed to receive the nose 25 of the fence lever 22. It will be understood that a tang on the end of the inner spindle and an appropriately shaped opening in the bridging slide, as shown in my said prior patent, may be substituted for the rack and pinion arrangement, if desired.

An arcuate boss 36 is also formed on the rear cover plate 12 of the lock casing which projects into overlapping relation with the drive cam periphery and terminates in stop shoulders 37 which limit the rotation of the drive cam 18 when the slide 27 is. in projected position and accommodate the projected end of the slide therebetween over a selected range of rotation of the drive cam corresponding to the rotation necessary to shift the bolt from projected to withdrawn position.

The structure thus far described is identical in structure and operation with that described in my said prior Patent No 2,575,674 except that a manually controllable knob is substituted for the key and pin tumbler arrangement disclosed in my said prior patent for manipulating the inner spindle.

As previously described, it has been found that if the drive cam 18 of this arrangement is rotated for a long period of time with the inner spindle control knob 35 shifted slightly to project the lower arcuate end surface 29 of the slide 27 against the inwardly facing surface of the arcuate boss 36, the end 29 of the slide may be abraded in some instances to a suflicient degree to permit the entrance portion of the drive cam gating 26 to be exposed to receive the fence lever nose by slight shifting of the slide 27 without projecting the lower end of the slide sufiioiently to be engaged by the stop shoulders 37 of the arcuate boss 36 upon rotation of the drive cam. When this condition exists, assuming that the fence is lowered sufficiently to rest upon the tumbler peripheries when the fence lever nose enters the entrance portion of the drive cam gating, the location of the tumbler gatings may then be detected by resorting to the manipulation procedure discussed above.

The purpose of this embodiment of the present invention is to insure that any rotation of the inner spindle knob 35 :sufiicient to move the bridging slide 27 at all will cause the slide to be shifted to fully projected position and thereby insure that the drive cam gating will either be completely bridged or the slide will be fully projected into position wherein the stop shoulders 37 restrict rotation of the drive cam. To this end, the inner spindle 33 is formed of a flat spring which is connected at opposite ends to the knob 35 and the pinion 32 which actuates the slide 27. A pair of vertically spaced shallow sockets 38 and 39' are provided on one lateral edge of the bridging slide 27 to be engaged by a spring pressed ball 40' which is mounted in. a suitablerecessin theadjacent portion of the drive cam and is resiliently urged by the coil spring 41 toward the slide 27. The lowermost slide socket 3'8 ispositioned to be received by the spring pressed ball 40 when the slide 27 is in closed or bridging position and the upper slide socket 39 is positioned to receive the spring pressed ball 40'when the slide is in fully projected position.

The operation of this mechanism is as follows:

Assuming that the dial 20 has beenmanipulated in the conventional manner to adjust the gatings of the three tumbler wheels 13, 14' and. 15 in registry with the fence 2'4 and to position the drive cam gating 26 to receive the fence lever nose 25, the inner spindle control knob 35 is then manually rotated through approximately degrees. The frictional forces between the spring pressed ball 40 and the slide socket 38 are such that over the major portion of this rotation oftheknob 35 the torque built up by rotation of the outer end of the flat spring forming the inner spindle 33 will be insufficient to overcome the restraining force of the spring pressed ball 40 on the slide 27. The inner spindle 33 in efiect stores up potential energy during. this phase of operation. Toward the end of the rotation of the knob 35 through 180 degrees, the tensional forces within the inner spindle 33 build up to a sufficient extent to overcome the restraining forces of the spring pressed ball 40 and the potential energy stored up in the inner spindle is thereupon released to effect rotation of the inner end of the spindle and the pinion 32. connected thereto to project the slide 27 fully until the upper slide socket 39 comes into alignment with the spring pressed ball 40. Therefore, by this arrangement, it is not possible for persons to project the bridging slide 27 only partially from its bridging positionv to enable the fence lever nose to be lowered into entrance of the drive cam gating and still prevent suflicient projection of the lower end of the slide from the drive cam periphery to be engaged by the stop shoulders 37'. By this arrangement, full throw of the slide 27 from its closed. position to its projected position is insured. Further, the imposition of sufiicient projecting force on the slide 27. to effectively abrade the lower end 29 thereof by rotating the same in contact with the inner surfaces of the arcuate boss 36 is rendered infinitely more difficult. By the simple expedience herein disclosed, this approach to surreptitious detection of the combination of a lock is thwarted.

Figures 5 to 7 disclose another species of the present invention. This species involves the adaptation of. the present invention to a combination. lock of the type disclosed in US. Patent No. 2,722,820 issued to M. E; Cofi'ey on November 8, 1955. The basic combination lock structure of this species employs three peripherally gated tumbler wheels 45-47, inclusive, journalled for rotation on a usual tubular tumbler post projecting from the front wall of the lock casing 48. A tubular dial spindle 49 extends through the tumbler post and the safe door .and has fixed thereto at its outer end a combination lock dial 50 and at its inner end a drive cam 51. The drive cam 5l'has the usual peripheral gating 52 adapted to receive the nose 53 of a fence lever 54 whose other end is pivoted to the bolt 55. The usual fence 56 projects from the fence lever in overlying relation to the tumbler peripheries. The shielding means of this species comprises a shielding disk 57 adapted to overlie the rear face of the drive cam 51' and has an uninterrupted peripheral flange 58 to encase the periphery of the drive cam 51 and shield the same from contact with the fence lever nose 53'. The shielding disk 57 is suitably fixed to an inner spindle 59 for rotary and axial movement with the inner spindle. The spindle 59 extends through a central bore in the dial spindle 49 and the dial 50' and terminates in a push button 60 which is received within a recess 61 in the knobportion of the dial50. A suitable 'coil spring 62 surrounds the inner'spindle'59 and is conipressed between the inner wall of the push button 60 and the opposite shoulder portion of the recess 61 to continuously urge the inner spindle 59 outwardly of the dial 50 and the shielding disk 57 toward the drive cam 51. As is disclosed in detail in the said Coffey Patent No. 2,722,820, the inner spindle 59 is axially adjustable relative to the dial spindle 49 but is keyed with the dial spindle 49 to prevent relative rotation of the spindles. The shielding disk 57 is provided with an arcuate slot 63 which is adapted to receive a guard pin 64 which projects forwardly from the rear wall 65 of the lock casing 48 when the inner spindle 59 and shielding disk 57 are urged rearwardly against bias of the spring 62. The function of the guard pin 64 is to limit the extent of rotation of the drive cam 51 when the flanges 58 of the shielding disk 57 are shifted rearwardly out of protecting relation with the drive cam periphery.

The inner spindle mechanism 59 is modified in accordance with the present invention to insure full throw of the shielding disk 57 from its forwardly projected protecting position to a rearwardly projected position wherein the guard pin 64 is seated in the arcuate slot 63 and the drive cam periphery is exposed to be contacted by the fence lever nose 53. To this end, the inner spindle 59 is formed of a forward section 66 and a rearward section 67. The innermost end of the forward spindle section 66 extends in telescoping relation into a tubular sleeve 68 for axial movement relative thereto and is resiliently connected to the forwardmost end portion of the sleeve 68 by means of a coil spring 69 which is affixed at one end by spot welding or the like to the forwardmost spindle section 66 and is similarly affixed at its other end to the sleeve 68. The forward end of the rear spindle section 67, in the preferred embodiment, is rigidly fixed to the rearmost end portion of the sleeve 68, but may be resiliently secured thereto by a coil spring in the identical manner that the coil spring 69 interconnects the sleeve 68 with the spindle section 66. The sleeve 68 is freely slidable axially in a complementary bore formed within the dial 50 and is provided with two outwardly opening sockets 70 and 71 which are spaced apart along an axis paralleling the axis of the spindle sections 66 and 67. Cooperating with the sockets 70 and 71 is a spring pressed ball 72 seated in a radial bore 73 in the dial 50 and resiliently urged by the coil spring 74 toward the sleeve 68. The tension of the coil spring 74 may be conveniently adjusted by means of a set screw 75 threaded into the radial bore 73.

Upon manipulation of the dial in the usual manner, the peripheral gatings of the tumbler wheels 45-4'7 and of the drive cam 51 will be aligned with the fence 56 and fence lever nose 53. During this manipulation of the dial, the fence lever nose 53 will be shielded from Contact with the drive cam periphery by means of the peripheral flange 58 on the shielding disk 57 which surrounds the drive cam periphery. If the push button 60 is then depressed axially toward the lock casing 48, initial movement of the push button 60 and the outward spindle section 66 will effect progressive compression of the coil spring 69 interconnecting the spindle section 66 with the sleeve 63. During the initial portion of this movement, however, the spring pressed ball 72 will frictionally restrain the sleeve 68, the rearward spindle section 67 and the shielding disk 57 against axial movement. When, however, the compression of the spring 69 reaches such a point that the internal tension of the spring 69 is sufiicient to overcome the restraining force of the spring pressed ball 72, the ball 72 is forced out of the socket 71 and the sleeve 68, rearward spindle section 67 and shielding disk 57 are shifted axially rearwardly under the force of the energy stored up in the spring 69 to fully project the shielding disk 57 out of guarding relation with the drive cam periphery and seat the guard pin 64 in the arcuate slot 63. This movement of the shielding disk 57 permits the fence lever nose 53 to drop into the drive cam gating so that upon rotation of the dial 60 in the proper direction, the drive cam 51 will shift the fence lever so as to retract the bolt 55. The length of the arcuate slot 57 into which the guard pin 64 is projected is just sufficient to accommodate this amount of rotation of the drive cam. It will be understood that rearward movement of the sleeve 68 and the components fixed thereto under the influence of the spring 69 is terminated when the socket 70 comes into alignment with the spring pressed ball 72. The push button 60 must be grasped and drawn axially away from the dial 50 to return the shielding disk 57 to guard position. During this movement of the inner spindle assembly, the forward edges of the peripheral flange 58 of the shielding disk which taper to a sharp edge are progressively forced between the fence lever nose 53 and the drive cam periphery to elevate the fence lever to normal position spaced from the drive cam and tumblers.

If the resilient connection between the forward and rearward inner spindle sections 66 and 67 were omitted and the inner spindle consisted of an uninterrupted inner spindle, as is disclosed in the Coffey patent, the direct connection between the shielding disk and the inner spindle push button would permit arcuate manual control of the degree of rearward movement imparted to the shielding disk and, if the forward edges of the shielding disk peripheral flanges became worn away, it is possible that premature lowering of the fence lever nose into operative coupling with the drive cam gating may be affected without sufficient rearward movement of the shielding disk to bring the arcuate slot 63 of the shielding disk into intercoupled relation with the guard pin 64. In this situation, sufficient movement could be imparted to the drive cam when the same is engaged by the fence lever nose to permit the security of the lock to be breached by manipulation procedures.

A further modification is illustrated in Figures 8 to 10. The combination lock therein shown is the type disclosed in detail in my copending application Serial No. 249,495, filed October 3, 1951, and entitled Combination Lock, and particularly the embodiment disclosed in Figures 4 to 5A, inclusive, thereof. This lock comprises the usual tumblers 76 journalled for rotation on a tubular tumbler post projecting from the forward wall of the lock casing 77. An axially adjustable dial spindle assembly 78 has a dial 79 fixed to the forward end thereof and the usual drive cam 80 keyed to the rear end thereof. A fence lever 81 is pivoted to the bolt 82 and has a fence lever nose 83 adapted to cooperate with the peripheral gating of the drive cam and a fence 84 adapted to be received in the peripheral gatings of the tumblers. In this species the length of the fence lever nose 83 relative to the position of the lower face of the fence 84 is such that the fence 84 is spaced slightly from the tumbler peripheries when the fence lever nose is in contact with the drive cam periphery.

An integral projection 85 is engaged by the lip 86 of a leaf spring 87 which is aifixed to and depends from the upper wall of the lock casing 77 and has a portion lapping and lying immediately behind the rear surface of the drive cam 80. The lip 86 is normally biased by the leaf spring 87 to support the fence lever 83 in elevated position spaced from the periphery of the drive cam 80. Upon inward axial movement of the dial 79 and drive cam 80, when the tumblers are adjusted with their gatings in registry with the fence, the rear face of the drive cam will engage the lapping portion of the leaf spring 87 and flex the same rearwardly out of supporting relation with the fence lever projection 85 to lower the fence lever nose 83 into the drive cam gating. The drive cam 80 is provided with the usual forwardly projecting drive pin 88 adapted to engage the conventional fly associated with the rearmost tumbler wheel, the length of the drive pin 88 being such that it is shifted rearwardly a suflicient distance to decouple the same from the tumbler fly when genesis projecting arcuate boss 91 on the'rear cover plate 92 of thel'ock casing 77, the spacing of the stop shoulders 90 being suflicient to accommodate enough rotary movement of the drive cam 80 and guard pin 89 to retract the bolt 82 through the interconnection of the fence lever nose 83 with the drive cam 80. The arcuate boss 9t projects forwardly a sufficient distance to prevent rearward axial movement of the drive cam or dial spindle whenthe guard pin- 89 is out of registry with the relieved area between' the stop shoulders 90'.

It is possible that the lip' 86 of the leaf spring 87 may become so deformed or that the relationship" between the parts of the lock may vary as a result of long use to a sufficient degree that release of the fence lever 81 might be affected during rearward axial movement of the drive cam 80 before the drive cam has been shifted far enough to' project the guard pin 89 into the area between the stop shoulders 90. If this occurs, security of the lock may be broken by manipulation of the lock in the usual manner. 7

To avoid this, the dial spindle unit 78 is divided into a forward section 93 and a rearward section 94. The rearward section 94 is fixed as by welding or the like to a sleeve 95 and has a diametrically extending key-way 96 therein. The forward spindle section 93 terminates rearwardly in a key 97 which is slidably fitted in the key-way 9 6 topermit relative axial displacement of the two spindle sections 93' and 94 and couple the same together for corresponding rotary movement. The rearward portion of the spindle section 93 is also surrounded by a coil spring 93 corresponding to the spring 69 in the previously described embodiment which is" welded at one end to the forward spindle section 93 and at its other end tothe sleeve 95. The sleeve 95 is also provided with a pair of annular grooves 99, 100 which are spaced axially of the spindle sections by a distance corresponding to the full throw desired for the drive cam 80' cooperating with a spring pressed ball 101, which is resiliently biased toward the sleeve by the spring M2, in the same manner described in connection with the preceding embodiment.

With this arrangement, when the tumblers and driving cam have been appropriately adjusted in accordance with the combination, the initial inward movement of the dial 79' and forward spindle section 93 progressively compresses the spring 98 to a point where the tension of the spring is sufiicient to overcome the restraining force of the spring pressed ball 1t and release the spring pressed ball from the groove '99. The sleeve 95, rearward spindle section 94 and drive cam are then shifted rearwardly by 'the'release of the energy stored in the spring 98' to the rearrnost position of the drive cam as determined by the position of the socket 99. In this position, the guard pin 89 is fully projected into the space between the stop shoulders 90 thereby insuring that the rotationof the drive cam 80 will be limited by the stop shoulders 90. The drive cam 85 may then be rotated through the limited are by means ofthe rotary connection afforded by the key-way '96 and key 97 to shift the fence lever 81 and bolt 82 to unlocked position. Reverse rotation of the driving cam returns the bolt to projected position and outward force upon the dial 79' will effect return of the drive earn and dial to the to wardmost position by this progressive tensioning of the spring 98' until the force of the same is sufficient to overcome the restraining force of the spring pressed ball 101 in the groove 100.

It will be apparent from the above description that each of the above embodiments of the invention have as a common feature the provision of means between the drive cam shielding mechanism and the manipulating facility therefor for storing uppotential energy during initial move ment' of the manipulating facility and then releasing the stored up energy automatically at sometime during the movement of the manipulating facility and apply the same to the shielding mechanism t'o'force the shielding mechanism fully from shielding position to non-shielding position. This expedient defeats attempts to partially shift the shielding mechanism to intermediate positions wherein contact between the fence and tumblers and bet-Ween the fence lever nose and drive cam can be established while the drive cam is capable of driving the tumblers to a substantial extent, and thereby protects the lock against breach of security by surreptitious manipulation.

While several preferred and practical embodiments of the invention have been disclosedin the above description, it will be understood by those skilled in the art that the disclosure represents exemplary embodiments and that other re-arrangements of parts cooperable to carry out the inventive concept are to be regarded as within the purview of the invention.

I claim:

1. In a combination lock of the type having a plurality of peripherally recessed tumbler wheels, a rotatable drive cam for adjusting said tumblers, a bolt, a fence lever pivotally mounted on said bolt having a fence extending in overlying relation with said tumbler peripheries and a depending nose adapted to overlie and selectively engage the periphery of said drive cam, said drive cam having a peripheral gate therein for accommodating said fence lever nose to permit said fence to seat in said tumbler recesses for moving said bolt, shielding means associated with said drive cam normally positioned to shield said drive cam gate against entry of said fence lerver nose therein, and manipulatable means adjustable over a preselected range of movement between limit positions for shifting said shielding means from said shielding position to a non-shielding position relative to said drive cam gate; the improvement in which comprises resilient energy storage means interposed between said manipulatable means and said shielding means and intercoupling the same, and restraining means for resiliently holding said shielding means against displacement from said shielding position and for releasing said shielding means for movement by said energy storage means from said shielding position to said non-shielding position when a preselected quantity of potential energy is stored insaid energy stor age means, said energy storage means being conditioned by adjustment of said manipulatable means to store up potential energy while said restraining means is holding said shielding means against displacement and expend the energy stored therein upon said shielding means to shift the same fully from said shielding position to said nonshielding position when said restraining means releases said shielding means.

2. In a combination lock of the type having a plurality of peripherally recessed tumbler wheels, a rotatable drive cam for adjusting said tumblers, a bolt, a fence lever pivotally mounted on said bolt having a fence extending in overlying relation with said tumbler peripheries and a depending nose adapted to overlie and selectively engage the periphery of said drive cam, said drive cam having a peripheral gate therein for'accommodating said fence lever nose to permit said fence to seat in said tumbler recesses for moving said bolt, shielding means associated with said drive cam and supported for movement between first and second spaced positions relative to said fence lever for shielding said drive cam gate against entry of the fence lever nose therein when said shielding means occupies said first position and for exposing said drive cam gate to entry of said fence lever nose when said shielding means occupies said second position, a manually adjustable member adjustable over a preselected range of movement between limit positions, and means for limiting movement of said drive cam when said shielding means occupies said second position, the improve- .ment in which comprises resilient energy storage means interposed between said manually adjustable member and said shielding means, restraining means for resiliently holding said shielding means and a portion of said storage means against displacement from each of said first and second positions during an initial portion of adjustment of said manually adjustable member through said range of movement to produce storage of a preselected quantity of potential energy in said energy storage means corresponding at least to the work required to shift said shielding member fully from one of said positions to the other of said positions, said restraining means being conditioned to release said shielding means for displacement by said energy storage means when said preselected quantity of potential energy is stored in said energy storage means, and means intercoupling said shielding means with said energy storage means to expend the energy stored in said storage means in shifting said shielding means fully from one of said positions to the other of said positions when said restraining means releases said shielding means.

3. In a combination lock of the type having a plurality of peripherally recessed tumbler wheels, a rotatable drive cam for adjusting said tumblers, a bolt, a fence lever pivotally mounted on said bolt having a fence extending in overlying relation with said tumbler peripheries and a depending nose adapted to overlie and selectively engage the periphery of said drive cam, said drive cam having a peripheral gate therein for accommodating said fence lever nose to permit said fence to seat in said tumbler recesses for moving said bolt, shielding means associated with said drive cam normally positioned to shield said drive cam gate against entry of said fence lever nose therein, and a manually adjustable member adjustable over a preselected range of movement between limit positions for shifting said shielding means from said shielding position to a non-shielding position relative to said drive cam gate; the improvement in which comprises restraining means for resiliently holding said shielding means against displacement from said shielding position and from said non-shielding position, and spring means interposed between said manually adjustable member and said shielding means and intercoupling the same to be stressed by adjustment of said manually adjustable member over an initial portion of said range of movement thereof and store up sufiicient energy to displace said shielding means fully from said shielding position to said nonshielding position and release said restraining means from holding relation with said shielding means, said spring means being coupled to said shielding means to expend the energy stored in said spring means in shifting said shielding means from said shielding position to said non-shielding position upon release of said shielding means.

4. In a combination lock of the type having a plurality of peripherally recessed tumbler wheels, a rotatable drive cam for adjusting said tumblers, a bolt, a fence lever pivotally mounted on said bolt having a fence extending in overlying relation with said tumbler peripheries and a depending nose adapted to overlie and selectively engage the periphery of said drive cam, said drive cam having a peripheral gate therein for accommodating said fence lever nose to permit said fence to seat in said tumbler recesses for moving said bolt, shielding means associated with said drive cam normally positioned to shield said drive cam gate against entry of said fence lever nose therein, a manually adjustable member adjustable over a preselected range of movement between limit positions for shifting said shielding means between gate shielding and non-shielding positions, and means for limiting rotation of said drive cam when said shielding means occupies said non-shielding position; the improvement in which comprises spring means interposed between said manually adjustable member and said shielding means and intercoupling the same, and restraining means for resiliently holding said shielding means against displacement from said shielding position for restraining a portion of said spring means intercoupled with said shielding means against displacement during adjustment of said manually adjustable member through said range of movement thereof to internally stress said spring means, and said restraining means being adjusted to be overcome by the stress in said spring means and release said shielding means for displacement by said spring means when said internal stressing of said spring means is sufficient to displace said shielding means fully from said shielding position to said non-shielding position.

5. In a combination lock of the type having peripherally recessed tumblers, a rotatable driving cam for adjusting said tumblers having a peripheral gate therein, a bolt, a fence lever for operating said bolt having a nose selectively engageable with said fence, shielding means normally positioned to prevent entry of said nose in said gate during manipulation of said driving cam to adjust said tumblers, manually adjustable means for shifting said shielding means between gate-shielding and nonshielding positions, and means imposing a selected restraint upon rotation of said driving cam when said shielding means is shifted fully to non-shielding position; resilient means intercoupling said manually adjustable means with said shielding means for transferring movement of said manually adjustable means to said shielding means, means restraining said shielding means against movement from said gate-shielding position during initial adjustment of said manually adjustable means for storing up energy in said resilient means upon adjustment of said manually adjustable means while rendering said shielding means nonresponsive to such adjustment, and means for releasing said restraining means from restraining relation with said shielding means when said stored up energy exceeds the work required to fully shift said shielding means from said gate-shielding position to said non-shielding position whereby said shielding means is shifted fully between said positions relative to said manually adjustable means by said stored up energy.

6. In a combination lock having peripherally recessed tumblers, a peripherally recessed rotatable drive cam, means supporting said drive cam for axial movement between first and second spaced positions of axial adjustment, said drive cam having means for adjusting said tumblers when said drive cam is positioned at said first position of axial adjustment, a bolt, a lever for operating said bolt having fence means thereon overlying said tumbler peripheries and a portion to overlie and selectively engage the periphery of said drive cam, means normally supporting said lever to space said lever portion and fence means out of operative engagement with said drive cam and tumblers when said drive cam is disposed at said first position of axial adjustment for adjusting the tumblers and positioned to be moved out of supporting relation with said lever during axial shifting of said drive cam between said first position of axial adjustment and said second position and prior to registry with said second position, and means disposed rearwardly of said drive cam cooperating with said drive cam to limit rotation of the drive cam when the latter occupies said second position of axial adjustment; the improvement in which comprises a manually adjustable member for axially shifting said drive cam means, a coil spring coaxially aligned with the axis of adjustment of said drive cam interposed between said manually adjustalble member and said drive cam means, means securing one end of said coil spring to said manually adjustable member and the other end thereof to said driving cam, and spring pressed means resiliently biased toward said drive cam means for restraining the same against displacement from said first position and from said second position, said spring pressed means holding said drive cam means and the associated end of said coil spring against displacement during a portion of adjustment of said manually adjustable member through said range" of movement to cause said coil spring to store 11p potential energy when the end of said coil spring affixe'd to' said manualiy adjustable member is displaced by movement of the latter and being adjusted to be overcome by the stress in said coil spring when the stored potential energy exceeds the Work required to shift said drive cam means to said second position to release said drive cam means for axial displacement b'ysaid 'coil spring to said second position.

7. A combination lock comprising a lock casing, a plurality of disk-like tumblers interconnected by lost motion drive connections and being operably mounted within said housing, said tumblers each having a peripheral gate therein, a disk-like drive cam rotatably supported within said housing, a lost motion driving connection between said drive cam and one of said tumblers, a bolt slida'bly mounted on said housing, a movable fence lever secured to said bolt for operating the same and having a fence overlying said tumble-rs and a fence lever nose for selectively engaging the periphery of said drive cam, said drive cam having a gate in the periphery thereof to accommodate said fence lever nose and permit said fence to seat in said tumbler gates for moving said bolt, a drive cam shaft fixed to said drive cam and projecting axially thereof, a dial shaft axially aligned with said drive cam shaft and having an externally exposed dial fixed to one end thereof, said drive cam shaft and said dial shaft terminating adjacent each other, means supporting said shafts for axial movement, a leaf spring stop mounted in said casing in the path of axial movement of said drive cam and having a lip portion engaging and supporting said fence lever and biased to maintain said fence out of engagement with said tumbler peripheries and said nose out of engagement with said cam periphery, said stop means being flexed out of operative contact with said fence lever on axial movement of said drive cam from one position of axial adjustment to a second spaced position of axial adjustment to permit said fence lever nose to seat in said drive cam gate on registry of said tumbler gates with said fence, a sleeve member coaxially aligned with said shafts and located in the region of the adjacent termini thereof for accommodating axial movement of said dial shaft relative thereto and coupled to said drive cam shaft to impart movement thereto upon movement of said sleeve member, a coil spring coaxially related to said shaft axes and affixed at one end to said adjacent end of said dial shaft and at the other end to said sleeve, and spring pressed ball means coacting with said sleeve to resiliently hold said sleeve either of two spaced positions of axial adjustment corresponding to said two positions of said drive, said spring pressed ball means being adjusted to be released from holding relation with said sleeve by said coil spring when the internal stress of said coil spring reaches a condition at least sufiicient to shift said drive cam and its associated shaft from said first position to said second position, whereby said spring pressed ball mean restrains said sleeve and the associated end of said coil spring against displacement during initial axial adjustment of said dial to store up sufficient energy in said coil spring by axial movement of said dial to shift said drive cam between said two positions and then releases said sleeve to expend said stored energy in shifting said drive cam from one of said positions to the other of said positions.

8. In a combination lock of the type comprising a plurality of selectively adjustable tumbler wheels each having a peripheral recess, a bolt, a hollow spindle having a dial aflixed to one end thereof, a drive cam aflixed to the other end of said hollow spindle for adjusting said tumblers and for actuating said bolt, a fence lever pivotally connected to said bolt and having a tumbler engaging fence and a nose for engaging the periphery of said drive cam, said drive cam having a peripheral gate adapted to receive said nose for moving said bolt when said recesses in said tumblers are positioned to register with said fence, a bridging slide movable radially of said drive cam from ash'iel'ding" position to a nod-shielding position, said slide having an arcuate surface adapted to bridge said drive cam gateto shield the gate against entry of said nose whensaid slide is in" said shielding position, means extending through said hollow spindle and intercoupled with said slide for shifting said slide radially of said drive cam and means in the path of rotatiori of said slide when said slide is in non-shielding position for limiting rotation of said drive cam to a minor arc; the improvement in which comprises an elongated flat spring extending through said hollow spindle for rotation about the longitudinal medial axis thereof having a. manipulatable knob secured to the outer end thereof in juxtaposed relation to said dial and rotatable means on the inner end thereof for imparting radial movement to said slide, spring pressed means in said drive cam urged toward said slide, said slide having a pair of spaced sockets therein positioned to receive said spring pressed means when said slide is in shielding position bridging said drive cam gate and when said slide is in a non-shielding position exposing said drive cam gate to receive said fence lever nose, said spring pressed means being adjusted to restrain said slide and the associated end of said spring against displacement during a portion of rotary movement of said knob from preselected positions to impose a torsional stress on said spring adequate to fully shift said slide from shielding position to non-shielding position and then release said slide when said spring acquires said torsional stress to respond to said torsional stress and be shifted by said spring.

9. In a combination lock of the type comprising a plurality of selectively adjustable tumbler wheels each having a peripheral recess, a bolt, a hollow spindle having a dial aflixed to one end thereof, a drive cam affixed to the other end of said hollow spindle for adjusting said tumblers and for actuating said bolt, a fence lever pivotally connected to said bolt and having a tumbler engaging fence and a nose for engaging the peripery of said drive cam, said drive cam having a peripheral gate adapted to receive said nose for moving said bolt when said recesses in said tumblers are positioned to register with said fence, a bridging slide movable radially of said drive cam from a shielding position to a non-shielding position, said slide having an arcuate surface adapted to bridge said drive cam gate to shield the gate against entry of said nose when said slide is in said shielding position, means extending through said hollow spindle and intercoupled with said slide for shifting said slide radially of said drive cam and means in the path of rotation of said slide when said slide is in non-shielding position for limiting rotation of said drive cam to a minor arc; the improvement in which comprises an elongated flat spring extending through said hollow spindle for rotation about the longitudinal medial axis thereof having a manipulatable knob secured to the outer end thereof in juxtaposed relation to said dial and rotatable means on the inner end thereof for imparting radial movement to said slide, spring pressed ball means in said drive cam urged toward said slide, said slide having a pair'of spaced sockets therein positioned to receive said spring pressed ball when said slide is in shielding position bridging said drive cam recess and when said slide is in a non-shielding position exposing said drive cam recess to receive said fence lever nose, said spring pressed ball being in restraining engagement with said slide and the associated end of said spring holding the same against displacement during the initial portion of the rotation of said knob and the outer end of said spring from preselected limit positions to effect resilient rotary distortion of said leaf spring about its longitudinal axis and store up potential energy therein by rotation of said knob and being adjusted to be released from said slide by the stresses in said spring when said stored up energy is suflicient to fully project the slide to non-shielding position for expending the stored up energy of said spring upon said slide to shift the same fully from shielding position to 2,575,674 non-shielding position. 2,722,820 2,744,396 References Cited in the file of this patent 2,807,954

UNITED STATES PATENTS 5 1,734,579 Higgins Nov. 5, 1929 735,143 2,115,849 Gustavson May 3, 1938 763,597

'16 Miller Nov. 20, 1951 Cofiey Nov. 8, 1955 Nagy et a1 May 8, 1956 Miller Oct. 1, 1957 FOREIGN PATENTS Great Britain Aug. 17, 1955 Great Britain Dec. 12, 1956 

